SME-08B21, B22, B23

Optical Encoder IC

1. OVERVIEWThe SME-08B2x is a 3-channel optical encoder IC with digital output.
The SME-08B2x consists of an LED and an OEIC (Opto-Electric Integrated Circuit) in a single package.
The light emitted from the LED is projected onto the code wheel, and the reflected light is received by a photodiodeto detect the relative movement between the SME-08B2x and the code wheel. In addition, Z-phase, the origin signal,
is output by setting a pattern on the code wheel for origin detection.
The resolution can be adjusted with a built-in interpolation circuit.

2. FEATURES
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Compact clear molded package (L=3.95mm W=3.4mm H=1.0 mm)
80µm resolution (When interpolation factor is 1)
LED and OEIC fabricated in a single package
3-channel digital output
Bult-in interpolation circuit (Interpolation factor can be selected from 4, 8, 16)
Supports 3.3 V and 5 V supply voltages
27mA current consumption
LED wavelength: 850nm

3. BLOCK DIAGRAM

VDD_D

VDD_A

PD array for incremental/Z-phase
LEDIV Convertor

Amplifier

LEDDriver
CHACHBCHZ

SEL1Interpolator
SEL2

VSS_D

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

VSS_A

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Optical Encoder IC

4. PIN LAYOUT

CH A

VDD_D

VDD_A

8716

VSS_A

5SEL1

9CH B

2VSS_D
34CH ZSEL2Top View

5. PIN DESCRIOTION
No.

Name

I/O

1CHAO

A-phase digital incremental signal

2CHBO

B-phase digital incremental signal

3

CHZO

Z-phase digital origin signal

4SEL2I

Interpolation setting input 25SEL1IInterpolation setting input 26VSS_A-Ground7

VDD_A-

Supply voltage

8

VDD_D-

Supply voltage

9

VSS_D
I/O type I: Input

Function

GroundO: Output

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

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SME-08B21, B22, B23

Optical Encoder IC

6. ABSOLUTE MAXIMUM RATINGS
Parameter

SymbolConditions

RatingUnit

note-0.3 to 7.0

V*1

Supply voltage

VDD

VDD_A, VDD_D pins

Input voltage

VIN

SEL1, SEL2 pins

-0.3 to VDD+0.3

V*1

Output voltage

VOUT

CHA, CHB, CHZ pins

-0.3 to VDD+0.3V*1,*2

Storage temperature

TSTG-40 to 85℃*3*1: Parameters must not exceed ratings, not even momentarily. If a rating is exceeded, there is a risk of IC failure,
deterioration in characteristics, and decrease in reliability.
*2: VDD in absolute value ratings refers to the recommended operating voltage V DD value.
*3: Stored separately in Nitrogen (N2) atmosphere or vacuum.

7. RECOMMENDED OPERATING CONDITIONS
VSS=0V codewheel ROP:11mm
Parameter
Supply voltage

SymbolConditions

MIN

TYP

MAX

UnitVDD

Between VDD and VSS terminals
VDD_A=VDD_D
VSS_A=VSS_D

4.555.5

3.0

3.3

3.6--40-85°CV

Operating temperatureTa

Code wheel radial misalignment

ER-0.2+0.2mm

Code wheel tangential misalignment

ET-0.2+0.2mm

Code wheel Gap

G0.5

1.0mm

0.75

* Operation outside the recommended operating conditions may adversely affect reliability. Use only within
specified ratings

8. ELECTRIC CHARACTERISTIC
8.1. DC Characteristics
VSS=0V、Ta=25C
Parameter

SymbolCondition

MINTYPMAXUnitCurrent consumption

IDD1

Include LED load current
At no output load-2740mA

High-level output voltage

VOH

IOH=1.5mA

VDD-0.4

VDDV

Low-level output voltage

VOL

IOL=-1.5mA

VSS

0.4

V

*Under our installation conditions and typical recommended operating conditions

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

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SME-08B21, B22, B23

Optical Encoder IC

8.2. AC Characteristics
VSS=0V、Ta=25C
Parameter

SymbolCondition

FOUT

SEL1 = H, SEL2 = H
Interpolation factor: 4
SEL1 = L, SEL2 = L
Interpolation factor: 8
SEL1 = H, SEL2 = L
Interpolation factor: 16

Output frequency

Output signal rise timetrCL≦50pF

Output signal fall timetf

CL≦50pF

Output stable latency

twaitMINTYP

MAX--240-

-

480-

-

960-

-

100

ns-

100

ns-

-

ms

1Unit

kHz

*Under our installation conditions and typical recommended operating conditions

9. FUNCTION DESCRIPTION
The light emitted from the LED is projected onto the code wheel, and the reflected light is received by a photodiodeto detect the relative movement between the SME-08B2x and the code wheel. In addition, Z-phase, the origin signal,
is output by setting a pattern on the code wheel for origin detection.
The SME-08B2x also has a built-in interpolation circuit, which can be set using the SEL1 and SEL2 pins.

9.1. Interporation Function
The interpolation factors can be set by the SEL1 and SEL2 pins.
SEL1

SEL2Interpolation factor

HH4LL

8H

L

16

9.2. LED Auto Power Control (APC) Brightness Adjustment Function
The SME-08B2x has a built-in automatic LED brightness adjustment function (Auto Power Control) to compensatefor LED brightness variations and temperature fluctuations.

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

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SME-08B21, B22, B23

Optical Encoder IC

10. TIMING DIAGLAM

Direction of code wheel rotation: CCW* The Z-phase pulse width is determined by each product.
Product name
SME-08B21
SME-08B22
SME-08B23

Parameter Definition
Parameter
Output cycle
Output cycle error
Pulse width (Duty)
Pulse width (Duty) error

SymbolC
CP
P

StateS

State errorSPhase differenceφ

Phase error

φOptical Radius

ROPZ-phase pulse widthPZ

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

Z-phase pulse width90°e
180°e
360°e

Phase A and B output 1 cycle 360°e
Output cycle deviation
Output signal duty ratio
Deviation of the pulse width from the ideal value of 180°e
Phase A/B rising (falling) edge interval.
4 states per output cycle, ideal value is 90°e
Deviation of each state width from 90°e
The distance between the center of the High state of phase A and the center ofthe High state of phase B. Ideal value 90°e
Deviation from the ideal phase value of 90°eDistance from the center of rotation of the code wheel to the optical center of theencoder ICZ-phase pulse width2024.05
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SME-08B21, B22, B23

Optical Encoder ICEncoder Output Characteristics

Code wheel: ROP = 11mm
Interpolation factor
Parameter
SymbolUnit
4
8
16
Output cycle error
C
(±17)
(±28)
(±35)
e
Pulse width (Duty) error
P
(±14)
(±18)
(±22)
e
Phase errorφ(±5)(±8)(±9)
eState error
S
(±8)
(±10)
(±13)
e
Z-phase pulse width (Gated 90°)
PZ909090
eZ-phase pulse width (Gated 180°)
PZ
180180180
e
Z-phase pulse width (Gated 360°)PZ
360360360e*Under our installation conditions and typical recommended operating conditions

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

2024.05
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SME-08B21, B22, B23

Optical Encoder IC

11. RECOMMENDED CODE WHEEL CONDITIONSParameter
Pattern width ratio (reflective/non-reflective)
Incremental pattern cycle
Incremental pattern width
Pattern length
Reflectance (reflective part)
Reflectance (non-reflective part)

Symbol
WW/WB
PPWW,WBLWRFMin
0.91.860-Typ18040-Max
1.110Unit

Note

μmμmmm%%

ROP=(PPR*PP)/2

unit:mm

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

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SME-08B21, B22, B23

Optical Encoder IC

12. CODE WHEEL MOUNTING CONDITIONS
The optical center of the encoder IC should be aligned with the ROP.
Please evaluate the mounting conditions thoroughly before setting the encoder IC.

13. TYPICAL APPLICATIONS

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

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SME-08B21, B22, B23

Optical Encoder IC

14. PACKAGING DIMENSIONSTopview
OpticalCenter

3.40±0.20

2.62

3.95±0.20

0.50

Sideview2

1.00±0.1

0.52

Sideview1

8×0.45

Bottomview
8×0.35

2.15

0.90

0.90

0.50

0.95

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

0.95

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Optical Encoder IC

15. USAGE AND PRECAUTIONSThis product is designed and manufactured to the generally accepted standards of reliability as expected for use ingeneral electronic and electrical equipment, such as personal equipment, machine tools, and measurement
equipment. This product is not designed and manufactured to be used in any other special equipment requiringextremely high level of reliability and safety, such as aerospace equipment, nuclear power control equipment, medicalequipment, transportation equipment, disaster prevention equipment, security equipment.
If you wish to use this product in equipment requiring extremely high level of reliability, please contact our sales
department or representative in advance.
In the event that this product is used in such equipment, please take scrupulous care and apply fail-safe techniques
including redundancy and malfunction prevention in order to prevent damage to life, health, property, or infrastructureetc. in case there is some malfunction in the product.

Please pay your attention to the following points at time of using the products shown in this document.
1. The products shown in this document (hereinafter ”Products”) are designed and manufactured to the generally
accepted standards of reliability as expected for use in general electronic and electrical equipment, such as
personal equipment, machine tools and measurement equipment. The Products are not designed and manufactured
to be used in any other special equipment requiring extremely high level of reliability and safety, such as aerospaceequipment, nuclear power control equipment, medical equipment, transportation equipment, disaster prevention
equipment, security equipment. The Products are not designed and manufactured to be used for the apparatus thatexerts harmful influence on the human lives due to the defects, failure or malfunction of the Products.
If you wish to use the Products in that apparatus, please contact our sales section in advance.
In the event that the Products are used in such apparatus without our prior approval, we assume no responsibility
whatsoever for any damages resulting from the use of that apparatus.
2. NPC reserves the right to change the specifications of the Products in order to improve the characteristics orreliability thereof.
3. The information described in this document is presented only as a guide for using the Products. No responsibility isassumed by us for any infringements of patents or other rights of the third parties which may result from its use. No
license is granted by implication or otherwise under any patents or other rights of the third parties. Then, we assume
no responsibility whatsoever for any damages resulting from that infringements.
4. The constant of each circuit shown in this document is described as an example, and it is not guaranteed about its
value of the mass production products.
5. In the case of that the Products in this document falls under the foreign exchange and foreign trade control law orother applicable laws and regulations, approval of the export to be based on those laws and regulations are necessary.
Customers are requested appropriately take steps to obtain required permissions or approvals from appropriate
government agencies.
6. When exporting customer’s products that use the Products, customers must comply with the "Foreign Exchange andForeign Trade Act" and other export-related laws and regulations, and follow the necessary procedures inaccordance with those laws and regulations. Do not use the Products in equipment whose sale is prohibited byexport-related laws and regulations ("JP Foreign Exchange and Foreign Trade Act" and "US Export Administration
Regulations", etc.). In addition, please do not sell the Products to users who are expected to use it for the above
equipment or companies in its supply chain. If a user who uses module parts and equipment using the Products is acompany suspected of violating human rights, please do not sell the above parts and equipment to that user.

SEIKO NPC CORPORATION
2-9-4, Taito, Taito-ku,
Tokyo 110-0016, Japan
Telephone: +81-3-6747-5300
Facsimile: +81-3-6747-5303
https://www.npc.co.jp/
Email:sales@npc.co.jp

SME-08B21, B22, B23 Data Sheet
Preliminary-DE240080-E001

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